Klaus
Hoppe

The urban wasteland on the vacant lot is the example par excellence of this. The longer the state of uncertainty persists, the more spontaneous plant communities develop, all the way to pioneer forests. These random wastelands are therefore cyclical and can hardly be influenced.

Can planning nevertheless create open spaces that allow for natural dynamics? And can near-natural landscapes on the outskirts of the city be linked to the inner city by green connecting lines, thus creating open spaces that are not isolated from each other but are connected to each other via a large urban green network and allow constant exchange of species. Furthermore, this network must be made usable and developed as an everyday quality to enable an experience of nature. These are all tasks that the Grüne Netz Hamburg has accepted as its mission.

The idea of a network-like green infrastructure for Hamburg began more than 100 years ago when the present city-state of Hamburg still consisted of many independent cities. Gustav Oelsner developed three green belts for Altona, a connecting green corridor was built in the independent town of Wandsbek, and Fritz Schumacher outlined the urban development of a future Hamburg in a summarizing and forward-looking manner in his «Fingerplan». In this plan, it is the white areas that were to be laid out as a future open space structure as deliberate green caesuras, thus turning the city and landscape into a living green «organism».

In the 80s of the 20th century, landscape planning at the state level began to secure what already existed and to connect it in planning terms to form an open space network system for the entire city, first referred to as a «green network». Two green rings, twelve landscape axes, parks and green axes—all together and connected with each other take up the existing open space structures and develop from them an independent open space concept in the binding landscape program.

The first green ring is the remnant of the old medieval fortifications, which, after losing its military significance, was kept free of buildings and partially landscaped, as in many cities. The fact that today such a large part has been built on or covered with traffic infrastructure can be regretted afterwards, but it is irreversible.

The second green ring is the «trap line» of the green network: a 100 km long circular path through the fraying edge of the city. A path that sometimes runs very narrowly as a trail through small wildernesses, sometimes traverses large parks in wide paths, such as the Altona Volkspark, and sometimes finds its asphalt track along busy main roads in an accompanying green fugue. Allotment gardens are also traversed, offering glimpses into the souls of gardeners.

It is not a really grown, clearly readable border of the city that one experiences while walking along it, but one that is set by planning. A city edge that allows individual free spaces and at the same time provides a deep insight into the city system, which becomes increasingly disordered towards the edge. This borderline encompasses the densified core city of Hamburg. It is an adventure route for urban pioneers, a testing ground for art in the urban in-between zones, and a sporting challenge for Hamburgers who want to circumnavigate their own city with their own muscle power.

Wayfinding and orientation systems are a consistent theme addressed by the green network. The goal is to enable intuitive «flowing» movements through the city that can find support and backbone in the greenery, but also achieve a degree of recognition.

One of the twelve landscape axes was selected as a pilot area for 5 years in 2015: the axis along the Horner Geest edge, the «Landschaftsachse Horner Geest». The break edge between the marsh and the Geest is one of the few topographical features in Hamburg that can be experienced in the cityscape. A special feature that is celebrated in the west of Hamburg with the best residential locations along the Elbchaussee, but hardly appears in the urban structure in the east of Hamburg. The great destruction caused by the war and the car-oriented development took a particular toll here.

In recent years, a number of measures have been implemented to strengthen this landscape axis and make it visible. Green milestones at 200m intervals clock the distance to the city or the landscape. Citizen projects help to create identification of the residents with «their axis». Unused lawns become meadows. Starlings gradually took to the 200 green new starling boxes. They understood the invitation to come from the outskirts further into the city, not least because the food supply has improved. The starling had been chosen as the key species together with the Nature Conservation Union, as it was not too demanding a bioindicator and could make successes visible early on.

In 2016, thanks to the NABU (The Nature And Biodiversity Conservation Union) popular initiative, the Grüne Netz Hamburg was both secured in its existence and its further development structurally anchored by a contract for Hamburg’s green spaces. The protection mechanism of this contract secures the existence of the inner-city open space system (in which every encroachment must be compensated on a large scale!)—this is unique in Germany. And the fact that annual funds are made available for the acquisition of land (3 million Euros) and further development (4 million Euros), including the personnel to implement this, is certainly also remarkable.

How does the casual magic of experiencing nature on the outskirts of the city come about? The fluttering lemon butterfly, the powerful dandelion blossom in late spring, the fluttering evening swift in the sunset. Just like people’s sensibilities, such natural phenomena cannot be planned; they can only be made possible. Therefore, it needs care. Care that becomes more extensive towards the edge as the intensity of use decreases. But even extensive care must actually take place. It requires much more understanding of natural dynamics than regular mowing with a lawn mower. Meadows must be mowed at the right time, clearings in the forest must be kept free of woody plants but not all foliage completely blown away, and paths into and through the greenery must remain walkable but should not be paved. There is a fine line between what is perceived by most as neglect and what is associated with disdain. The acceptance of a lower mowing density of open areas and more extensive maintenance of roadsides must be perceived as a quality in order to avoid a negative connotation. After all, the wild does not only have a positive connotation. Especially the dark, uncontrolled can also quickly become a place of fear. This does not matter to fox and hare, but not to the district politician.

Biodiversity is an unwieldy term that usually gets stuck in the discussions of specialized planning. What constitutes the value of biodiversity to the average city dweller? Is it the polyphonic birdsong, the colorful flowering meadow. Certainly. Even without knowing the individual bird species, a wider species spectrum of birds and their songs is unconsciously perceived as particularly rich. The meadow functions excellently as a horticultural production for the city dweller particular during the blooming season, although it has been relieved of its original function as a food production.

The large-scale nature conservation project «Natürlich Hamburg!», which has already been launched and is being funded with 16 million euros by the Federal Ministry of the Environment, will be allowed to address precisely these issues over a period of 12 years. The task is to change the city’s green space management in the long term. In 20 selected parks, these changes will be systematically prepared and implemented on the basis of carefully drawn-up maintenance plans.

And: Last but not least, it is also important to conquer the city’s stone structure in order to draw the green network more finely meshed over the city. With the solar green roof obligation from 2027, this goal will become law in Hamburg. But the green roof strategy already pursued in Hamburg since 2013 is also having an impact. 175 ha of Hamburg’s roofs are green. The results of the insect surveys are surprising: 281 different beetle species have arrived on Hamburg’s green roofs. A unique beetle fauna has found its habitat here.

From the city-wide green network to the microcosm of the green roof—everything together serves nature in the city and gives its inhabitants quality of life.